#include "tensorflow/core/lib/io/record_writer.h"

#include "tensorflow/core/public/env.h"
#include "tensorflow/core/lib/core/coding.h"
#include "tensorflow/core/lib/hash/crc32c.h"

namespace tensorflow {
namespace io {

RecordWriter::RecordWriter(WritableFile* dest) : dest_(dest) {}

RecordWriter::~RecordWriter() {}

static uint32 MaskedCrc(const char* data, size_t n) {
  return crc32c::Mask(crc32c::Value(data, n));
}

Status RecordWriter::WriteRecord(StringPiece data) {
  // Format of a single record:
  //  uint64    length
  //  uint32    masked crc of length
  //  byte      data[length]
  //  uint32    masked crc of data
  char header[sizeof(uint64) + sizeof(uint32)];
  core::EncodeFixed64(header + 0, data.size());
  core::EncodeFixed32(header + sizeof(uint64),
                      MaskedCrc(header, sizeof(uint64)));
  Status s = dest_->Append(StringPiece(header, sizeof(header)));
  if (!s.ok()) {
    return s;
  }
  s = dest_->Append(data);
  if (!s.ok()) {
    return s;
  }
  char footer[sizeof(uint32)];
  core::EncodeFixed32(footer, MaskedCrc(data.data(), data.size()));
  return dest_->Append(StringPiece(footer, sizeof(footer)));
}

}  // namespace io
}  // namespace tensorflow